/*  
  -- The Lime II Project -- 

  A tuplespaces-based middleware for coordinating agents and mobile hosts.
  Copyright (C) 2005.
  Gian Pietro Picco, Amy L. Murphy, Lorenzo Bellini.

  This library is free software; you can redistribute it and/or
  modify it under the terms of the GNU Lesser General Public
  License as published by the Free Software Foundation; either
  version 2.1 of the License, or (at your option) any later version.

  This library is distributed in the hope that it will be useful,
  but WITHOUT ANY WARRANTY; without even the implied warranty of
  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
  Lesser General Public License for more details.

  You should have received this copy of the GNU Lesser General Public
  License along with this library; if not, write to the Free Software
  Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA 
 */

package lime2.ca.treeplain;

import lime2.ca.EngMsg;
import lime2.*;

import java.io.*;
import java.net.*;
import java.util.logging.Logger;

/**
 * A "receiver" of remote multicast messages. It listens "on" a UDP socket,
 * receives remote ops and enqueues them. Please note that in multicast
 * communication we have to discard datagrams that are looped-back: we check the
 * sender port and address of the datagram; we don't want to go through
 * deserialization (overhead of deserializing the looped back messages). The
 * convention is that datagrams are sent using the unicast port number of the
 * host.
 * 
 * @author Gian Pietro Picco
 * @author Amy Murphy
 * @author Lorenzo Bellini
 */

class TreePlainMulticastReceiver extends Thread {
	// private data members
	private DatagramSocket dsock, ssock;
	private int portcheck;
	private boolean shutdown;

	/**
	 * Constructor method.
	 * 
	 * @param dsock
	 *            datagram socket to use for listening
	 * @param ssock
	 *            datagram socket used for sending
	 * @param portcheck
	 *            in multicast communication we have to discard looped-back
	 *            datagrams; sender datagram port for this host; <code>-1</code>
	 *            disables the check
	 */
	TreePlainMulticastReceiver(DatagramSocket dsock, DatagramSocket ssock,
			int portcheck) {
		super();
		this.dsock = dsock;
		this.ssock = ssock;
		this.portcheck = portcheck;
		this.shutdown = false;
	}

	/**
	 * Run method.
	 */
	public void run() {
		// initializations
		byte[] buffer = new byte[LimeConstants.UDP_BUFFER_SIZE];
		InetAddress here = LimeServer.getServer().getUnicastAddress();
		int port = LimeServer.getServer().getUnicastPort();

		// loop
		while (!shutdown) {
			try {
				DatagramPacket dp = new DatagramPacket(buffer, buffer.length);
			
				assert(dsock != null);
				dsock.receive(dp);
				if (portcheck == -1 || dp.getPort() != portcheck
						|| !(here.equals(dp.getAddress()) && port == dp.getPort()))
				// discards its own looped-back datagrams
				{
					Object o = Serializer.deserialize(dp.getData());
				/*	System.out.println(LimeServer.getServer().getServerID().getHost().getHostAddress() +" Receive the Engaged Hello message from " 
							+ dp.getAddress() + ":" + dp.getPort());

				*/	if (o instanceof RemoteOp) {
						RemoteOp ro = (RemoteOp) o;
//						System.out.println("recevier multicast remote op:" +ro.toString()+" from " +ro.getSourceString());
					}
					if (o instanceof EngMsg) {
						EngMsg em = (EngMsg) o;
						TreePlainCA.pd.collectMsg(em);
						//reply to the source for its calculation of rtt

//						System.out.println(LimeServer.getServer().getServerID().getHost().getHostAddress() +" Send the Hello Reply message to " 
//								+ em.source.getHost().getHostAddress());
						
						new HelloReplyServant(em).start();
					} else
					
						TreePlainCA.queue.add(o);
				}
			} catch (IOException ioe) {
				ioe.printStackTrace();
			} // just prints stack trace: "robust" server
		}
		// end loop
		dsock.close();
		ssock.close(); // .. when we stop multicast communication, we have to
						// close also the datagram sender socket !!
		ssock = null; // .. from now on trying to send a multicast message will
						// result in a TOTAL failure
	}

	/**
	 * Shuts the receiver down.
	 */
	void shutdown() {
		shutdown = true;
	}
	
	class HelloReplyServant extends Thread {
		private EngMsg msg;
		
		private Logger LOG = Logger.getLogger(this.getClass().getName());
		
		HelloReplyServant(EngMsg msg) {
			this.msg = msg;
		}
		
		public void run() {
			msg.type = LimeConstants.HELLO_REPLY;
			Connection c = null;
			try {
				c = Connection.get(msg.source);
			} catch (IOException ioe) {
				LOG.severe("fail to get connection to " + msg.source);
			}
			
			msg.source = Location.HERE.getID();
			
			// temporary variables
			boolean end = false;
			int retries = 0;

			// partial failure ?
			while (!end) {
				try {
					c.send(msg);
					end = true;
					/*System.out.println("Send the Engaged Hello Reply message to " 
							+ msg.source.getHost().getHostAddress());
					*//*System.out.println(LimeServer.getServer().getServerID().getHost().getHostAddress() +" Receive the Reply Hello message from " 
							+ msg.source);*/
				} catch (IOException ioe) {
					if (++retries >= LimeConstants.RETRIES) {
						LOG.warning("send hello reply to " + msg.source + " fails after retries");
						end = true;
					}
				}
			}

			// irrelevant failure ?
			try {
				c.finished();
			} catch (IOException ioe) {
				LOG.warning("fail to correct close the connection to " + msg.source);
			}
		}
	}

}